Two ways to traverse a map (with sort)

Initialize a map

12345

map<string, string> Map = < /code>new  hashmap<string, string> (); map.put ( ,  "hell" map.put ( ,  "Hello" map.put ( ,  "hel" map.put ( ,  "Hello"

1, the first way, the general use of

1234	Set<String> keySet = map.keySet();for(String key : keySet) {    System.out.println("key= " + key + " and value= "+ map.get(key));}

2, the second way, the capacity of the recommended use of large

12345

Set<Map.Entry<String,String>> entySet =  map.entrySet();for(Map.Entry<String, String> entry : entySet) {    System.out.println("key= "+ entry.getKey() + " and value= "            + entry.getValue());}

The experiment found that the order of the output is chaotic, a sequence bar

1. Sort by key value

First write a sort class

1234567

privatestaticclassKeyComparator implements        Comparator<Map.Entry<String, String>> {    publicintcompare(Map.Entry<String, String> m,            Map.Entry<String, String> n) {        returnm.getKey().compareTo(n.getKey());    }}

Put the data in the list to use

123456789

list<map.entry<string, string>> list =  new  arraylist <map.entry<string, string>> (); list.addall (Map.entryset ());  keycomparator KC =  new  keycomparator (); collections.sort (list, KC); for   (iterator<map.entry<string, String >> it = List.iterator (); It &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP; .hasnext ();) { &NBSP;&NBSP;&NBSP;&NBSP; system.out.println ( It.next ());

2. Sort by value

1234567

privatestaticclassValueComparator implements        Comparator<Map.Entry<String, String>> {    publicintcompare(Map.Entry<String, String> m,            Map.Entry<String, String> n) {        returnm.getValue().compareTo(n.getValue());    }}

Sort output

12345678

list.clear();list.addAll(map.entrySet());ValueComparator vc = newValueComparator();Collections.sort(list, vc);for(Iterator<Map.Entry<String, String>> it = list.iterator();　　　　it.hasNext();) {    System.out.println(it.next());}

Tips: If you have any errors, please indicate that I will revise them in time.

Two ways to traverse a map (with sort)